The threat of a rapidly diminishing supply of fossil fuels has brought about a renewed interest in windmills and other fluid current motor devices. As windmill blades depend on a pitch angle to achieve rotation by the wind, the full force of a head wind can never be captured by the blades. Another limitation to the power producing capability of the conventional windmill is the limited amount of wind-bearing surface that can practically be provided on the blades. A further limitation is the wind drag loads created on the blades. These loads increase with increasing revolutions per minute and though the loads may be diminished somewhat by mechanisms that change the pitch angle of the blades for varying wind conditions, the drag load still exists.
Wind-driven devices have in the past operated in some applications around a vertical axis and in other applications around a horizontal axis. Mention is made of the distinction between vertical and horizontal axis-type devices because the present invention while adapted for operating in either a horizontal axis mode or a vertical axis mode is illustrated for vertical axis rotation for which it is deemed best suited.
U.S. Pat. Nos. 1,804,493; 3,093,194; 3,995,170; 4,115,027; 4,134,708; 4,142,822; 4,177,014; 4,197,055; and British Pat. No. 7176 are generally illustrative of wind-driven vertical axis devices. U.S. Pat. No. 2,542,522 is illustrative of a horizontal axis wind impeller and U.S. Pat. No. 4,137,005 illustrates an ocean wave driven apparatus operating with a horizontal drive axis.
Machines which utilize hydraulic force to perform work commonly take advantage of the weight or pressure of a liquid opposed by atmospheric pressure and converts this unbalanced force into rotary mechanical motion by waterwheels, turbines, or the like. The operation of these devices generally depend on a natural occurrence or the man-made creation of conditions that will allow a liquid to flow from a higher to a lower elevation. Whenever such conditions are either enhanced or created by man-made structures, such as dams or weirs, the task is often accomplished at enormous expense and at considerable risk of undesirable and irreversible environmental changes.
With the foregoing in mind, the present invention has as its general object that of providing a fluid current motor which may be employed with wind, water, or gas, i.e., generally with any type of fluid current, and with nonrigid sails so as to eliminate the need for windmill-type blades. The present invention also has as an object that of eliminating the need for dams, weirs, pipes, or other channeling devices in conjunction with employment of a fluid current motor in a stream, river, or ocean application, for example. Also, a further object is that of providing a fluid current motor adapted to capture substantially the full force of a fluid current to produce rotary motion and also to provide substantial fluidbearing surface with minimal drag.